Impedance matching buffered voltage divider

Thread Starter


Joined Oct 10, 2012
I have a quick question about a buffered voltage divider. I have two signals that can range from 0 to 5V that I need to scale down to 0 to 3V. I've chosen to do this with a voltage divider buffered through an opamp (schematic attached).

According to the data sheet, the output impedance of the voltage source is 470 ohms, and it wants at least 1 Mega Ohm of impedance on all analog and digital lines.

It seems to me that as long as the total equivalent resistance of the divider (R11 + R12) is ~1 mega ohm that the all will be well. Is this true or am I over simplifying it?



Joined Mar 14, 2008
That sounds correct.

You may be aware of this, but if the op amp only has a 3V supply, then the op amp must be a rail-to-rail type.